Multiple terminals are connectable to a single digital subscriber line with an Integrated Services Digital Network (ISDN) multipoint interface, defined in Recommendation I.430 of the International Telegraph and Telephone Consultative Committee (CCITT). The multipoint interface allows a customer to add terminals without providing additional wiring to the customer premises. In the past, switching systems stored data defining the call services for a terminal based on an equipment number associated with the line connecting the terminal to the switching system. Per-line service definition is ineffective, however, in a multipoint arrangement because it requires all terminals on a given digital subscriber line to have identical services. A customer, however, may need services to be defined individually for the terminals, requiring for example, differing feature button definitions for terminals on the same digital subscriber line.
One approach to the provision of individually defined services for terminals on a multipoint interface is to assign fixed terminal endpoint identifiers and store service data in the switching system based on these terminal endpoint identifiers. Requiring assignment of fixed terminal endpoint identifiers at subscription time, however, increases the administrative overhead for adding new terminals or moving existing terminals to new locations. In such an arrangement, moving a terminal between digital subscriber lines requires a service order to update the data stored in the switching system. Thus, before adding or moving terminals, a customer submits a service order request and then waits, possibly several days, until the request is processed and the data are updated. Furthermore, since unique terminal endpoint identifiers are required for each terminal, adding terminals, even terminals configured with the same services as another of the customer's terminals, requires a service order.
Moreover, in an arrangement having subscribed-to terminal endpoint identifiers, the switching system is unable to selectively address terminals in a message broadcast to all terminals on a digital subscriber line. CCITT Recommendation Q.931 requires broadcasting of certain messages such as messages offering incoming calls. If a customer requires a terminal to audibly alert for incoming calls to a particular directory number while another terminal on the same digital subscriber line silently alerts for calls to that directory number, conflicting call setup messages are required. The switching system needs a mechanism to address each message to the appropriate terminals while still broadcasting the messages to all terminals on the digital subscriber line. When broadcasting on a digital subscriber line, the switching system must use a global terminal endpoint identifier rather than the individual terminal endpoint identifiers of each terminal. Thus, even when the service information specifies conflicting terminating treatment for different terminals, the switching system is unable to address messages to the appropriate terminals.
In view of the foregoing, a recognized problem in the art is the difficulty of providing conflicting call services for terminals in a multipoint configuration and allowing broadcast messages to contain address information specifying particular terminals based on the services enabled for each terminal while limiting the administrative overhead for adding and moving terminals.